Kheloud successfully defended her Master’s thesis on A 3D Geometric Morphometric Analysis of Hippopotamid Crania at the Museum für Naturkunde / Potsdam University in January (yes we’re a bit late announcing it, but it was covid and all that, sorry Kheloud!). Examiners included Faysal Bibi, Ralph Tiedemann, and Jean-Renaud Boisserie. Nice job Kheloud, and congratulations! 🎉🦛
Below is the Abstract from Kheloud’s thesis work.
Hippopotamids represent a unique part of mammalian evolution, as they are amphibious herbivores and the only terrestrial representatives of Cetancodonta, the group containing hippopotami and whales (Boisserie et al. 2011). They are amongst the most commonly preserved mammals in Neogene fossil assemblages in Africa (Weston and Boisserie 2010). Although hippopotamids are a pivotal part of African megafaunas, with a past diversity of up to 40 species (Boisserie 2005), they have generally been understudied.
In this study, I conducted three-dimensional geometric morphometric analyses on 30 crania of at least four hippopotamid species. Four species are confirmed (Choeropsis liberiensis, Hippopotamus amphibius, Hippopotamus gorgops and Hippopotamus madagascariensis) as well as four undescribed crania from Tanzania and Sudan. By including fossil Pleistocene crania of the genus Hippopotamus, I analysed hippopotamid cranial shape evolution through the Pleistocene. The following hypotheses were tested: H1. Mid-Late Pleistocene Hippopotamus lie within the range of variation of extant Hippopotamus amphibius. H2. Choeropsis liberiensis and Hippopotamus madagascariensis share a similar growth allometry and are paedomorphic versions of Hippopotamus amphibius.
Results showed that the examined fossil hippopotamids mostly fell in the range of cranial shape variation of H. amphibius. Hippopotamus gorgops and H. madagascariensis were found slightly outside the range of variation, thus further supporting their designation as separate species. The Sudanese crania were found to be of smaller size than extant H. amphibius, indicating possible genetic bottlenecks in H. amphibius’ recent history. Furthermore, extant Hippopotamus and Choeropsis do not follow the same size-shape allometric trajectory. Further morphological analyses into the variation of Hippopotamidae is needed, in addition to molecular analyses.